Need help please

I have a 1996 waveblaster that would run great for about 3 or 4 seconds after you start it then it would only go about mph with just a little throttle, try go wide open and it just bogs out, let off the throttle and hold it open just a little and it would cruise at about 15 mph. Kill it, start it back up and it would run great for 3 to 4 seconds then this repeats all over. I rebuilt the carbs and it still does it. Run it on the trailer and it sounds like it is hitting the rev limiter. Just installed another CDI box and nothing changed. ANY HELP WOULD BE APPRECIATED.